German Offenlegungsschrift 30 34 467 relates to a pilot controlled pressure sequence valve which comprises a main valve and a pilot valve. Said pilot controlled sequence valve is used in an hydraulic apparatus for checking a connection between a source of pressure medium and an accumulator. Additional prior art is shown in the Mannesmann Rexroth prospectus RB 26410. This prior art is discussed in the introduction to the specification of said German Offenlegungsschrift 30 34 467. The object of said Offenlegungsschrift is to provide an apparatus which allows for a safe connection and separation of an accumulator. This object is solved by designing the valve member of the pilot control valve as a stepped spool, and moreover by providing two additional centrally located control spools which cooperate with the control edges of a valve housing containing the valve member. In accordance with a special design a check valve, the switch valve, the pilot valve and a throttle orifice are arranged in a common housing. With regard to the function of a sequence valve it is desirable to obtain a precise maintainance of the switch-off point and of the switch-on point for the accumulator to be charged. Moreover, for a pressureless circulation of the pump a circulation pressure should be obtained which is as low as possible, particularly, for reasons of saving energy.
Additional prior art is shown in German patent publications: DE 36 02 362 A1, DE 32 07 080 C2, DE 32 45 667 C2, DE 38 11 669 A1, De 28 14 301 C2.
It is an object of the present invention to provide a valve, in particular, a sequence valve specifically for checking a connection between a pressure source (pump) and an accumulator for such that a switching operation to the pressureless circulation (switch-off point) occuring tank pressure peaks are as low as possible and a jerk free switch-off operation is achieved while the pump circulating pressure nevertheless remains relatively small.